Synthetic method of biofuel oil used in low-temperature environment
By supercritical hydrolysis and molecular distillation under high temperature and high pressure conditions, short-chain fatty acids are broken, and the poor performance of biodiesel in low temperature environments is solved through the esterification reaction, and a wide freezing point range and oxidative stability are prepared. High low freezing point biofuel.
Patent Information
- Application Number
- CN202411769463.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-04
- Publication Date
- 2025-02-07
AI Technical Summary
The poor performance of existing biodiesel in low temperature environments limits its use as a substitute for diesel, kerosene and jet fuel in winter.
The supercritical hydrolysis technology under high temperature and high pressure is used to directly hydrolyze the oil and fat, and mixed fatty acids composed of carbon chain molecules of different sizes are obtained. The distillation and separation is carried out under low pressure through molecular distillation technology, and the chain is broken to generate short-chain fatty acids and alkanes, and finally through The esterification reaction results in low freezing point biofuel.
The prepared biofuels exhibit excellent low-temperature performance, with freezing point ranging from -35℃ to -70℃, have excellent oxidation stability and low greenhouse gas emissions, and have flash points above 60℃, making them safer and more convenient.
Smart Images
Figure CN119391485A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of bio-liquid fuel production, in particular to a method for synthesizing bio-fuel in a low-temperature environment. Background Art
[0002] The use of fossil energy has contributed to global warming and other environmental problems. Petroleum products account for about 45% of total U.S. carbon dioxide emissions, of which diesel fuel contributes about 17%. Biodiesel, renewable diesel, and sustainable aviation fuel (SAF) are considered effective solutions to reduce carbon emissions, but their poor performance at low temperatures limits their use in cold climates or as jet fuel. In contrast, the production of renewable diesel and SAF still requires high temperatures, high pressures, and large amounts of hydrogen, making their manufacturing costs high and their energy efficiency low.
[0003] The existing biodiesel production technology refers to the reaction of fats / oils with alcohols under catalytic conditions to generate fatty acid esters, which can be directly used as diesel fuel or mixed with petroleum-based diesel. Although biodiesel has cost advantages, its typical long carbon chain structure leads to poor low-temperature performance. The low-temperature performance of biodiesel limits its use as a substitute for winter diesel, kerosene and jet fuel. Therefore, a method for synthesizing biofuel for low-temperature environments is proposed. Summary of the invention
[0004] The purpose of the present invention is to provide a method for synthesizing biofuel for low temperature environment, so as to solve the problem that the existing biodiesel production technology mentioned in the above background technology refers to the reaction of fats / oils with alcohols under catalytic conditions to generate fatty acid esters, which can be directly used as diesel engine fuel or mixed with petroleum-based diesel. Although biodiesel has cost advantages, its typical long carbon chain structure leads to poor low temperature performance. The low temperature performance of biodiesel limits its use as a substitute for winter diesel, kerosene and jet fuel.
[0005] To achieve the above object, the present invention provides the following technical solution: a method for synthesizing biofuel for low temperature environment, comprising the following steps: S1. Remove impurities from waste grease; S2. Under high temperature and high pressure conditions, supercritical hydrolysis technology is used to directly hydrolyze oils and fats, and mixed fatty acids composed of carbon chain molecules of different sizes are obtained after oil hydrolysis; S3, using molecular distillation technology to distill and separate the mixed fatty acids under low pressure conditions; S4, the separated oil and short-chain fatty acids are collected in the short-chain fatty acid intermediate storage tank; S5, breaking the long-chain fatty acids to generate short-chain fatty acids and alkanes, removing the catalyst by filtration and collecting them into the short-chain fatty acid intermediate storage tank; S6, performing esterification reaction on the short-chain fatty acids to obtain a mixture; S7. Determine and obtain low freezing point biofuel.
[0006] Preferably, in S1, the waste oil is heated to 80-100°C and then passed through a bag filter and a centrifuge in sequence, wherein the filter bag of the bag filter has a mesh size of 100-150 meshes, the speed of the centrifuge is 5000 rpm, and the entire process takes 10-30 minutes.
[0007] Preferably, in S2, an automated continuous pipeline reactor with temperature control and flow rate control functions is adopted, and the reaction is continuously carried out in a flowing state. The reactor temperature is 250-300°C, the pressure is 5-10MPa, and the residence time of the oil in the reactor is 1-3 hours. The reaction product contains fatty acids and glycerol. After 1-2 hours of stratification and standing, the fatty acids and glycerol can be effectively separated.
[0008] Preferably, in S3, distillation is carried out under a vacuum of less than 100 mmHg, the temperature is maintained between 100-150°C, and the residence time of the oil in the molecular distillation tower is 10-20 minutes.
[0009] Preferably, in S5, the long-chain fatty acid is heated to 300-400°C, 0.3-0.5% of a solid catalyst is added to promote the chain scission reaction, and the reaction is carried out in a nitrogen environment at 200-300°C, at normal pressure or slightly positive pressure, and the whole process takes 2-4 hours.
[0010] Preferably, in S6, the esterified alcohol may be a primary alcohol, a secondary alcohol or a tertiary alcohol.
[0011] Preferably, in S6, the alcohol for esterification is methanol among primary alcohols, methanol and short-chain fatty acids are mixed in a molar ratio of 2:1 to 3:1, 0.1-0.3% of the total mass of the reactants is added with an immobilized enzyme catalyst, the reaction mixture is heated to 60-70°C and stirred evenly, ultrasonic wave-assisted esterification is used, and the esterification reaction time is 4-6 hours.
[0012] Preferably, in S6, after the esterification is completed, the immobilized enzyme catalyst is filtered and recovered, and the mixture is allowed to stand for separation to remove water, and then the mixture is passed through a molecular sieve to further remove water, thereby obtaining a mixture of short-chain fatty acid methyl esters and alkanes.
[0013] Preferably, in S7, after measurement, the freezing point is -40°C and the closed cup flash point is 65°C, which can be used as a biofuel to replace -40 diesel in high-altitude cold areas.
[0014] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects: the biofuel prepared by the present invention exhibits excellent low-temperature performance, with a freezing point range of -35°C to -70°C, which shows its potential as a substitute for winter diesel, kerosene and jet fuel, and also has excellent oxidation stability and low greenhouse gas emissions. The flash point is higher than 60°C, and it is not a hazardous chemical, while the flash point of conventional -10, -20, -35, and -50 diesel is less than 60°C. In comparison, the present biofuel is safer and more convenient to store and use. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0016] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION
[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0018] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions under which this application can be implemented. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in this application without affecting the effects and purposes that can be achieved by this application. Example
[0019] In the prior art, biodiesel production technology refers to the reaction of fats / oils with alcohols under catalytic conditions to generate fatty acid esters, which can be used directly as diesel engine fuel or mixed with petroleum-based diesel. Although biodiesel has cost advantages, its typical long carbon chain structure leads to poor low-temperature performance. The low-temperature performance of biodiesel limits its use as a substitute for winter diesel, kerosene and jet fuel.
[0020] See also Figure 1The present invention provides a technical solution: a method for synthesizing biofuel for low temperature environment, comprising the following steps: S1. Remove impurities from waste grease by heating the waste grease to 80-100°C, and then passing through a bag filter and a centrifuge in sequence, wherein the mesh size of the bag filter is 100-150 meshes, the speed of the centrifuge is 5000 rpm, and the whole process takes 10-30 minutes; S2. Under high temperature and high pressure conditions, supercritical hydrolysis technology is used to directly hydrolyze oils and fats, and mixed fatty acids composed of carbon chain molecules of different sizes are obtained after oil hydrolysis; By adopting an automated continuous pipeline reactor with temperature control and flow rate control functions, the reaction is carried out continuously in a flowing state. The reactor temperature is 250-300°C, the pressure is 5-10MPa, and the oil stays in the reactor for 1-3 hours. The reaction product contains fatty acids and glycerol. After 1-2 hours of stratification and standing, the fatty acids and glycerol can be effectively separated. The operation is simple and the cost is low, which meets the needs of industrialization. S3, using molecular distillation technology to distill and separate the mixed fatty acids under low pressure conditions; Distillation is carried out under a vacuum of less than 100 mm Hg, and the temperature is maintained between 100-150°C to avoid thermal degradation of long-chain fatty acids. Short-chain fatty acids have a lower boiling point and are easy to evaporate at low temperatures. The residence time of oil in the molecular distillation tower is 10-20 minutes; S4, the separated oil and short-chain fatty acids are collected in the short-chain fatty acid intermediate storage tank; S5, breaking the long-chain fatty acids to generate short-chain fatty acids and alkanes, removing the catalyst by filtration and collecting them into the short-chain fatty acid intermediate storage tank; The long-chain fatty acids are heated to 300-400°C, and 0.3-0.5% of a solid catalyst (Na2O, K2O or Li2O) is added to promote the chain scission reaction. The catalyst promotes the cleavage of carbon-carbon bonds in organic molecules by providing alkaline sites, making it easier for long-chain fatty acids to cleave into short-chain fatty acids and alkanes. The reaction is carried out in a nitrogen environment at 200-300°C, at normal pressure or slightly positive pressure. The whole process takes 2-4 hours, and the generated short-chain fatty acids do not need to be separated from the alkanes. S6, performing esterification reaction on the short-chain fatty acids to obtain a mixture; The alcohol suitable for esterification can be a linear or branched structure, with a carbon number between 1 and 4. The alcohol for esterification can be a primary alcohol, a secondary alcohol or a tertiary alcohol. Methanol and ethanol are preferred alcohols, and isobutanol is also ideal. The alcohol for esterification is methanol among primary alcohols. Methanol and short-chain fatty acids are mixed in a molar ratio of 2:1 to 3:1. An immobilized enzyme catalyst of 0.1-0.3% of the total mass of the reactants is added. The reaction mixture is heated to 60-70°C and stirred evenly. This temperature range helps to increase the esterification reaction rate and prevent methanol from volatilizing. Ultrasonic waves are used to assist esterification to enhance mixing and reaction effects, effectively shorten reaction time, and increase esterification rate. The esterification reaction time is 4-6 hours. During the reaction, the degree of esterification is determined by acid value test to ensure that the short-chain fatty acids are converted into methyl esters. After the esterification is completed, the immobilized enzyme catalyst is filtered and recovered, and the water is removed by standing and separation. The water is further removed by molecular sieve to obtain a mixture of short-chain fatty acid methyl esters and alkanes. S7. The low freezing point biofuel is obtained by measurement. After measurement, the freezing point is -40°C and the closed cup flash point is 65°C. It can be used as a biofuel to replace -40 diesel in high-altitude cold areas.
[0021] In summary, the biofuel prepared by the present invention exhibits excellent low-temperature performance, with a freezing point range of -35°C to -70°C, which shows its potential as a substitute for winter diesel, kerosene and jet fuel, and also has excellent oxidation stability and low greenhouse gas emissions. The flash point is higher than 60°C, and it is not a hazardous chemical. The flash point of conventional -10, -20, -35, and -50 diesel is less than 60°C. In comparison, the biofuel is safer and more convenient to store and use.
[0022] It will be appreciated by those skilled in the art that the features described in the various embodiments and / or claims of the present invention may be combined and / or combined in various ways, even if such combinations and / or combinations are not explicitly described in the present invention. In particular, the features described in the various embodiments and / or claims of the present invention may be combined and / or combined in various ways without departing from the spirit and teachings of the present invention. All of these combinations and / or combinations fall within the scope of the present invention.
Claims
1. A method for synthesizing biofuel for low temperature environment, characterized in that: The following steps are involved: S1. Remove impurities from waste grease; S2. Under high temperature and high pressure conditions, supercritical hydrolysis technology is used to directly hydrolyze oils and fats, and mixed fatty acids composed of carbon chain molecules of different sizes are obtained after oil hydrolysis; S3, using molecular distillation technology to distill and separate the mixed fatty acids under low pressure conditions; S4, the separated oil and short-chain fatty acids are collected in the short-chain fatty acid intermediate storage tank; S5, breaking the long-chain fatty acids to generate short-chain fatty acids and alkanes, removing the catalyst by filtration and collecting them into the short-chain fatty acid intermediate storage tank; S6, performing esterification reaction on the short-chain fatty acids to obtain a mixture; S7. Determine and obtain low freezing point biofuel.
2. The method for synthesizing biofuel for low temperature environment according to claim 1, characterized in that: In S1, the waste oil is heated to 80-100°C and then passes through a bag filter and a centrifuge in sequence, wherein the filter bag of the bag filter has a mesh size of 100-150 meshes and the rotation speed of the centrifuge is 5000 rpm. The entire process takes 10-30 minutes.
3. The method for synthesizing biofuel for low temperature environment according to claim 1, characterized in that: In S2, by adopting an automated continuous pipeline reactor with temperature control and flow rate control functions, the reaction is carried out continuously under a flowing state. The reactor temperature is 250-300°C, the pressure is 5-10MPa, and the oil stays in the reactor for 1-3 hours. The reaction products contain fatty acids and glycerol. After 1-2 hours of stratification and standing, the fatty acids and glycerol can be effectively separated.
4. The method for synthesizing biofuel for low temperature environment according to claim 1, characterized in that: In S3, distillation is carried out under a vacuum of less than 100 mm Hg, the temperature is maintained between 100-150°C, and the residence time of the oil in the molecular distillation tower is 10-20 minutes.
5. The method for synthesizing biofuel for low temperature environment according to claim 1, characterized in that: In S5, the long-chain fatty acids are heated to 300-400°C, and 0.3-0.5% of a solid catalyst is added to promote the chain-breaking reaction. The reaction is carried out in a nitrogen environment at 200-300°C, at normal pressure or slightly positive pressure, and the whole process takes 2-4 hours.
6. The method for synthesizing biofuel for low temperature environment according to claim 1, characterized in that: In S6, the alcohol to be esterified may be a primary alcohol, a secondary alcohol or a tertiary alcohol.
7. The method for synthesizing biofuel for low temperature environment according to claim 1, characterized in that: In S6, the esterified alcohol is methanol among primary alcohols, and methanol is mixed with short-chain fatty acids in a molar ratio of 2:1 to 3:
1. 0.1-0.3% of the total mass of the reactants is added with an immobilized enzyme catalyst. The reaction mixture is heated to 60-70°C and stirred evenly. Ultrasonic wave-assisted esterification is used, and the esterification reaction time is 4-6 hours.
8. The method for synthesizing biofuel for low temperature environment according to claim 1, characterized in that: In S6, after the esterification is completed, the immobilized enzyme catalyst is filtered and recovered, and the water is removed by standing and separation, and then the water is further removed by passing through a molecular sieve to obtain a mixture of short-chain fatty acid methyl esters and alkanes.
9. The method for synthesizing biofuel for low temperature environment according to claim 1, characterized in that: In S7, it has been measured that the freezing point is -40℃ and the closed cup flash point is 65℃, which can be used as a biofuel to replace -40 diesel in high-altitude cold areas.